textproduct: Rapid City

KEY MESSAGES

- Isolated to scattered showers and thunderstorms expected tonight, best chances across south central SD

- Slight risk (level 2 of 5) over western SD for Thursday with main threats being large hail and damaging winds.

- Unsettled weather continues through the rest of the week with near daily chances for afternoon showers/storms and temperatures in the 80s to 90s.

UPDATE

Issued at 928 PM MDT Tue Jun 30 2026

Upper trough will push through the region tonight, supporting pos theta-e adv across most of the FA, strongest across south central SD. MCS ongoing across western NE. Given location of the LL CAPE gradient, 0-3km shear vectors, and forcing aloft, expect the worst of this system will stay south of the scentral SD, with mainly the northern stratiform region and embedded TS expected to clip this area. NW of this system, expect ISOLD shra/ts overnight with little rainfall given high based nature and very dry ll profiles. Subsidence will spread over the region Wed morning behind the wave. Diurnal heating may be enough to support a few high based showers and TS off the BH in the afternoon and across far NW SD by evening. Gusty winds would be the only threat with these cells. SW flow will become established for the end of the week, with rounds of subtle mid-level impulses as LL moisture returns per ESE flow. Sufficient CAPE will be in place to support severe cells Thur and Friday, however, bulk shear is questionable attm with lack of stronger flow in the mid levels. Timing of mid level impulses will be key to see how things develop as well as the location of the low level moisture axis.

DISCUSSION

(This Evening Through Tuesday) Issued at 115 PM MDT Tue Jun 30 2026

Upper level analysis shows trof axis over the Rockies with southwest flow over the Northern Plains. Embedded shortwave sits centered over UT. The CWA sits under mostly clear skies with a few cumulus clouds developing over northwestern SD. Sunny and warm weather will prevail over the region through the afternoon before cloud cover increases in the evening as the upper level wave approaches the region. Storm chances will increase across the southern tier of our CWA through the evening hours. MU CAPE progged to increase to 1500-3000 J/kg over south central SD by midnight. CAMs show convection moving out of NE into the southern portions of our CWA. Widespread severe wx is not expected but we could see a few severe caliber gusts and large hail over south central SD overnight.

Storm chances return Wednesday afternoon as 500-1500 J/kg ML CAPE and effective shear of 30-45kt progged to develop over the Black Hills into south central SD. Isolated convection may develop over the Black Hills and along a dryline over southwestern into south central SD. A strong to severe storm may develop over the Black Hills and south central SD with large hail and damaging winds as the main hazards.

Weak shortwave moves through Thursday, 1500-3000 J/kg ML CAPE progged to develop over western SD by the afternoon hours with 30- 40KT effective shear. Convection should initiate along the higher terrain of the Bighorns and Black Hills and move eastward. NAM showing a strong signal of these cells growing into an MCS as they reach the western SD plains. The SPC has much of the western SD plains under a slight risk with the main hazards being large hail and damaging winds.

Deterministic guidance in good consensus of mostly zonal flow developing over the Northern Plains by the holiday weekend. Warm temperatures (in the 80s to 90s) with daily chances for afternoon storms will result.

AVIATION

(For the 06Z TAFS Through 06Z Wednesday Night) Issued At 1053 PM MDT Tue Jun 30 2026

Mainly VFR conditions are expected through most of the forecast period. Isolated thunderstorms will continue to push through the region during the overnight hours; mainly into south-central SD. MVFR/IFR conditions will be possible in the stronger storms, along with erratic gusty winds up to 40kts. Starting around 01/19-21z, isolated thunderstorms are possible over western South Dakota and the Black Hills, however, any storms that develop will be short-lived and will be mostly out of the region by the end of the forecast period.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.